What makes a sustainable diet?

Sustainability and diet

Sustainability is one of those environmental “hot topics”, which is so often talked about but rarely specifically explained. According to the Brundtland definition (presented in the Brundtland Report of 1987 to the UN General Assembly), sustainable development is:

“development that meets the needs of the present without compromising the ability of future generations to meet their own needs”.

As such, it is concerned with the well-being of future generations (linked to the availability of natural resources and general environmental quality), as well as that of the current population – the focus of this definition is on the well-being of people (Kuhlman & Farrington, 2010). Since this definition, sustainability has been presented as three overlapping categories; social, economic and environmental concerns (Fig 1).

Figure 1: Venn diagram illustrating the three overlapping spheres of sustainability: economic, social and environmental concerns.

Whether this framework works, is up to much discussion. Kuhlman & Farrington (2010) suggest that as the social and economic spheres primarily concern the present generations, and environmental concerns arguably focus instead on the preservation of resources for the future, the well-being of current generations is twice as weighted as the latter (Kuhlman & Farrington, 2010). As such, social and economic factors weigh more heavily in policy making compared to environmental problems: which might be why we are plagued with environmental crises today such as widespread pollution, deforestation and climate change.

Sustainability should provide a lens though which we can view a world in balance, where our needs are met without causing irreparable damage to our natural environment or global society. This is all well and good to say – but how can an individual make changes in their own lives to minimise their environmental footprint, and lead a more ‘sustainable’ life?

One of the most talked-about routes is of course diet. Rising incomes are shifting dietary habits across the globe, towards a more “westernised” diet based on refined sugars, fats, oils and meats (Tilman & Clark, 2014). It is projected that by 2050, these dietary trends will increase global greenhouse gas emissions (GHGs) from agriculture by 80% (Tilman & Clark, 2014), when the industry already releases a whopping 25% of greenhouse gases from all industries. In addition to this, demand for animal-based foods is expected to rise by 80% by 2050 based on 2006 levels, with demand for beef alone increasing by 95% (Ranganathan & Waite, 2016).

“Because it directly links and negatively affects human and environmental health, the global dietary transition is one of the great challenges facing humanity” – Tilman & Clark, 2014

These trends are alarming, when considering the population increase we are expected to see, as well as the types of food people want to consume with higher incomes (see here for more). Not to put the blame on meat consumption again, but it cannot be denied that beef production requires 20x the amount of land and emits 20x the amount of GHGs per unit of edible protein than plant-based sources like beans and lentils (Ranganathan & Waite, 2016), with 3x the land needed for chicken production in comparison. So, is the easiest way to be more sustainable to eat less meat? (Spoiler: the answer is yes).

Main Archives - McDonald's®
Figure 2: A most appetising Mcdonalds cheeseburger. Looks tasty, doesn’t it? Not so much when you consider that each pound of beef generates 25 pounds of CO2 emissions. The New York Times (2014) even goes as far to attribute a monetary value of $0.48 per burger as a healthcare cost, for the obesity it might eventually lead to(!).

Nutrition and diet

The Food Climate Research Network published an excellent in-depth discussion paper about sustainable diets, focusing on the nutritional benefit of different food types on the “Eatwell plate”, which summarises and quantifies the amount of each food group required to maintain a healthy diet (FCRN, 2014). It states that the lower the intake of fish, meat and dairy, the lower the environmental impact. As such, several “sustainable” diet frameworks have been identified, including the usual contenders of vegetarianism and veganism, as well as the Mediterranean diet and pescatarianism. These offer simple dietary “rules”, which can be followed by a consumer easily enough – don’t eat meat, don’t eat products containing milk etc. However, there is arguably no one-size-fits-all diet which not only is acceptable to everyone, but which also provides all the vital micro and macronutrients needed for the human body.

An interesting study by Macdiarmid et al., (2012) looked at creating the most sustainable healthy diet possible, without considering acceptability or palatability to people. It found that a diet consisting of only 7 foods, whole-grain cereal, pasta, peas, fried onions, brassicas, sesame seeds and confectionary, allowed a 90% reduction in greenhouse gases from a 1990 baseline. Admittedly, this diet would not appeal to many (or anyone at all), so the researchers then went on to consider acceptability, creating a new diet comprising 52 different food items (including meat, fish and dairy), which would reduce GHG emissions by 25% by 2020 from a 1990 baseline. This diet was referred to as the “sustainable diet”, which also came with a three-day meal plan featuring pleasant-sounding meals like “salmon with cream cheese topping, broccoli, new potatoes and carrots” (Macdiarmid et al., 2012).

Compared to the average UK diet, the sustainable diet contains a higher proportion of cereals, fruits, beans and pulses, whilst drastically reducing meat and high-sugar products (Macdiarmid et al., 2012). It could therefore be justified that a sustainable diet can include the consumption of meat, dairy and sugars, just in much lower quantities. But, as previously mentioned, the less animal products you can eat the better in terms of greenhouse gas emissions.

Caveats

A sustainable diet is not solely about what you eat. A sustainable foodie will also have to consider the chemicals and pesticides used to produce the food, from where it has flown in, the labour conditions for the harvesters and manufacturers, animal welfare, efficiency of production (e.g. organic vs. intensive farming), religious or cultural traditions, and of course nutrition (FCRN, 2014). For example, studies into organic produce in the UK showed that organic farming doesn’t always produce fewer GHG emissions than intensive farming per kg. As well as this, less intensive farming methods have higher land requirements to produce the same amount of food. What may appear to be the more “sustainable” choice might just be a ploy to sell you more expensive (and not necessarily more sustainable) items.

Summary

The discussion paper written by the FCRN (2014) summarises a sustainable healthy diet as having:

  1. Diversity in foods consumed
  2. High amounts of tubers, fruits and vegetables
  3. Meat and dairy consumed sparingly
  4. Fish coming from certified fisheries
  5. Limited consumption of sugary and fatty snacks

With enough googling, you can find online justification for several different diets and dietary trends. But flexibility is key, if these diets are to be maintained in the long term. Taking an item-by-item approach to your diet may therefore be more acceptable than banning food groups altogether, when considering both nutrition and sustainability. A brief summary of the environmental costs of different food groups may therefore be useful, if the reader wishes to make changes in their own diets (FCRN, 2014):

  1. Carbohydrates – the production of maize, wheat and potatoes has a relatively low GHG footprint, when rice is comparatively much higher, due to the production method used.
  2. Fruits and vegetables – Hard fruits (e.g. apples) and legumes have a comparatively lower GHG footprint compared to citrus fruits.
  3. Meat, fish and eggs – the average GHG emissions for beef consumed in the UK can vary from 12.1 to 32.0 kg CO2e/kg depending on where it was produced (Macdiarmid et al., 2012). Considerations around animal welfare are also important – intensive farming methods are more efficient in terms of land and resources but are generally disapproved of.
  4. Dairy – Dairy products emit medium-high levels of GHGs per kg consumed (Macdiarmid et al., 2012).
  5. Sugars and fats – Low GHG production relative to other food groups, but high land and water needs. Nutritionally very low (often referred to as “empty calories”), which some might describe as a waste of resources.

Being conscious of your consumption patterns, researching the impacts that your favourite foods have on the environment and society, and choosing the less GHG-intensive food options (but still nutritional) is a good start to making sustainable changes to your lifestyle.

References

FCRN (2014) What is a sustainable healthy diet? A discussion paper. [pdf] Available at: https://fcrn.org.uk/sites/default/files/fcrn_what_is_a_sustainable_healthy_diet_final.pdf (Accessed: 29/08/2019)

Kuhlman, T. & Farrington, J. (2010) What is sustainability?. Sustainability2(11), pp.3436-3448

Macdiarmid, J.I., Kyle, J., Horgan, G.W., Loe, J., Fyfe, C., Johnstone, A. & McNeill, G. (2012) Sustainable diets for the future: can we contribute to reducing greenhouse gas emissions by eating a healthy diet?. The American journal of clinical nutrition96(3), pp.632-639

Ranganathan, J. & Waite, R. (2016) Sustainable diets: what you need to know in 12 charts. [online] Available at: https://www.wri.org/blog/2016/04/sustainable-diets-what-you-need-know-12-charts (Accessed: 29/08/2019)

Tilman, D. & Clark, M. (2014) Global diets link environmental sustainability and human health. Nature515(7528), p.518

New York Times (2014) The true cost of a burger. [online] Available at: https://www.nytimes.com/2014/07/16/opinion/the-true-cost-of-a-burger.html (Accessed: 30/08/2019)

Published by avleveri

Hi! I'm Anna, an environmental science graduate from the UK. My main interests (if you can't already tell from my blog posts) are sustainability, consumption, conservation, nutrition, fitness and food! Lots of food.

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